Heat pumps



April 19, 1966 J, RNfs 3,246,482

HEAT PUMPS Filed Dec. 51, 1964' FIG.I.

l2 REVERSAL '3 VALVE I I I OUTDOOR INDOOR AIR COIL T (f AIR COIL .'28ACCUMULATOR' CAPILLARY CAPILLARY TUBE TUBE COOLING HEATlNG-- v T I l2REVERSAL. l4 VALVE n, OUTDOOR \l" moooa AIR con. m AAlRcolL I O T l w II7 uh COMPRESSOR 28 ACCUMULATOR CAPILLARY OAPILLARY TUBE TUBE GOOLINGHEATING--?' INVE NTOR= JAMES R. HARNISH, BY W ATTORNEY United StatesPatent Oflice.

3,246,482 HEAT PUMPS James R. Harnish, Staunton, Va., assiguor toWestinghouse Electric Corporation, Pittsburgh, Pa., a corporation ofPennsylvania 7 Filed Dec. 31, 1964, Ser. No. 422,664

' 8 Claims. (Ci. 62-324) This invention relates to heat pumps which usefixed flow restrictors such as capillary tubes for two-way expansionmeans.

It is well known that air-to-air heat pumps require larger refrigerantcharges during cooling operation than in heating operation. Some suchheat pumps use suction line accumulators to store the excess refrigerantduring heating operation. Such an accumulator separates lubrieating oilfrom the suction gas, and a bleeder must be provided at its bottom tometer oil return to the compressor. When such an accumulator ispartially filled with refrigerant, the bleeder also meters the flow of asubstantial amount of liquid refrigerant mixed with the oil, to thecompressor, and may dilute the oil in the crankcase of the compressor,resulting in adequatelubrication. Furthermore, the refrigerant in thecrankcase, during defrosting of the outdoor coil, may cause considerablefoaming and excess oil pumping, resulting in the compressor losing itsoil to the system.

This invention uses heat from the refrigerant liquid,

to boil off refrigerant liquid leaving an accumulator. There is nothermodynamic loss since the heat loss of the liquid provides a greaterrefrigerating effect. In one embodiment of this. invention, this isaccomplished by dividing a capillary tube serving as a two-way expansionmeans, into two lengths, and by connecting between the two lengths, alarger tube in heat exchange contact with the suction gas line to thecompressor. In another embodiment of this invention, a heat exchangecoil in'the bot-tom of a suction line accumulator is connected in thetube between the two capillary tube lengths.

An object of this invention is to reduce the quantity of refrigerantliquid flowing from an accumulator into a compressor during heatingoperation of a heat pump.

This invention will now be described with reference to the annexeddrawings, of which:

FIG. 1 is a diagrammatic view of a heat pump embodying this invention,and

FIG. 2 is a diagrammatic view of another heat pump embodying thisinvention.

Description of FIG. 1

The discharge side of a refrigerant compressor C is connected bydischarged gas tube 10 to a conventional reversal valve RV which isconnected by tube 11 to one side of an outdoor air coil 12, and by atube 13 to one side of an indoor air coil 14. The valve RV is alsoconnected by tube 16 to the upper portion of a conventional suction lineaccumulator 17. Within the accumulator 17 is a U-shaped tube 18 havingan open end 19 near the top of the accumulator, and connected at itsother end through suction gas tube 20 to the suction side of thecompressor C. The base of the tube 18 has an oil bleed hole 29 in itscenter. The other side of the outdoor air coil 12 is connected by tube22 to one end of capillary tube 23, the other end of which is connectedto 'a tube 24 which is connected to a tube 25 in heat exchange contactwith the suction gas tube 20. The tube 25 is connected by tube 26 to oneend of another capillary tube 27, the other end of which is connected bytube 28 to the other side of the indoor air coil 14.

Cooling operation of FIG. 1 In the cooling operation of FIG. 1 as shownby the solid-line arrows, discharge gas from the compressor C issupplied through the tube 10, the reversal valve RV, and the tube 11into the outdoor air coil 12 operating as a condenser. Refrigerantliquid from the coil 12 flows through the tube 22, the capillary tube23, the tubes 24, 25 and 26, the capillary tube 27 and the tube 28 intothe indoor air coil 14 operating as an evaporator, the capillary tubes23 and 27 operating as expansion means. Gas from the indoor coil 14flows thorugh the tube 13, the reversal valve RV and the tube 16 intothe accumulator 17. Gas from the accumulator 17 flows through the tubes18 and 20 to the suction side of the compressor C. The refrigerantliquid flowing through the tube 25 heats the suction gas flowing throughthe tube 20, but there is no thermodynamic loss since the liquid issubcoo-led.

Air heating operation of FIG. 1

As shown by the dashed-line arrows, discharge gas from the compressor Cflows through the tube 10, the reversal valve RV and the tube 13 intothe indoor air coil 14 operating as a condenser. Refrigerant liquid fromthe coil 14 flows through the tube 28, the capillary tube 27, the tubes26, 25 and 24, the capillary tube 23 and the tube 22 into the outdoorair coil 12 operatingas an evaporator, the capillary tubes 27 and 23operating as expansion means. Gas and unevaporated liquid flow from thecoil 12 through the tube 11, the reversal valve RV and the tube 16 intothe accumulator 17. Gas separated from the liquid within the accumulatorenters the open end 19 of the tube 18. Refrigerant liquid Within theaccumulator 17 enters the tube 18 through the oil bleed hole 29 so thatgas and some liquid flow through the suction gas tube 20- towards thesuction side of the compressor C. Heat from the high pressure, liquidflowing through the tube 25 which is in contact with the tube 20,evaporates the refrigerantliquid within the tube 20 so that gas onlyflows into the suction side of the compressor. The liquid within thetube 25 is subcooled.

, The upstream capillary tube 27, by restricting the fiow of refrigerantliquid from the coil 14, causes some liquid to be backed up in thelatter, providing further subcooling, and preventing any high pressuregas from the coil 14 which would reduce the capacity of the system, andincrease the power required, from entering the tube 28.

. The downstream capillary tube 23 maintains the pressure and thetemperature of the liquid Within the tube 25 high enough to effect thedesired heat transfer.

The capillary tubes 27 and 23 are fixed restrictors, and together havelengths and internal diameters sized for the required expansion duringair cooling operation, and are, in effect, two lengths of the usual,single, capillary tube used for two-way expansion.

Description of FIG. 2

FIG. 2 is similar to FIG. 1, except that a coil 30 is placed in thebottom of the accumulator 17, and is connected between the capillarytube 23 and the tube 24. Corresponding components of FIGS. 1 and 2 havethe same reference characters applied thereto.

Cooling operation of FIG. 2

The cooling operation of FIG. 2 is the same as that of FIG. 1 exceptthat the liquid from the capillary tube 23 flows through the coil 30before entering the tube 24 instead of flowing directly into the latter.By charging the system with more refrigerant than is required to satisfyboth the indoor coil 14 and the outdoor coil 12, the excess refrigerantliquid will collect in the accumulator 17 in heat exchange contact withthe coil 30. Since the compressor C pumps gas boiled olf in both theindoor coil 14 and the accumulator 17, excess liquid flows from theoutdoor coil 12, through the tube 22, the capillary tube 23,

Patented Apr. 19, 1966 the coil 30, the tubes 24, 25 and 26, thecapillary tube 27 Heating operation of FIG. 2

The heating operation of FIG. 2 is the same as that of FIG. 1, exceptthat the refrigerant liquid leaving the tube 24, instead of flowingdirectly into the capillary tube 23, flows through the coil 30 beforeentering the capillary tube 23. Heat from the refrigerant liquid flowingthrough the coil 30 evaporatessome of the excess refrigerant liquidflowing from the coil 12 into the accumulator 17, further subcooling theliquid to be evaporated. Again, excess liquid above the evaporation rateis fed to the evaporator, in this instance, the outdoor coil 12, toincrease the heat transfer, and the tube 11, the reversal valve RV andthe tube 16 flow less gas, reducing the pressure drop, and therebyincreasing the efiiciency of the system. Refrigerant liquid is preventedfrom entering the compressor C.

The system of FIG. 1 could also be provided with an excess charge ofrefrigerant, since the contact between the tubes 20 and 25 performs,although to a lesser extent,

the same function that the same contact, and the coil 30 of FIG. 2perform, and with the same benefits.

What is claimed is: I

1. A heat pump comprising a refrigerant compressor, reversal valvemeans, a discharge gas tube connecting the discharge side of saidcompressor to said valve means, an outdoor air coil, a second tubeconnecting. said valve means to said coil, an indoor air coil, a thirdtube connecting said valve means to said indoor coil, a suction lineaccumulator, a fourth tubeconnecting said valve means to saidaccumulator, a first fixed restrictor having a rela tively largeresistance to refrigerant flow, a fifth tube having a relatively smallresistance to refrigerant flow connecting said restrictor to saidoutdoor coil, a second fixed restrictor having a relatively largeresistance to refrigerant flow, a sixth tube having a relatively smallresistance to refrigerant flow connecting said secondrestrictor to saidindoor coil, a seventh tube having a relatively small resistance torefrigerant flow connecting said restrictors, and a suction gas tubeconnecting said accumulator to the suction side of said compressor, saidseventh tube being in heat exchange contact with said suction gas tube,said restrictors serving as two-way expansion means.

2. A heat pump as claimed in claim 1 in which said restrictors arecapillary tubes.

3. A heat pump as claimed in claim 2 in which there is provided a heatexchange coil in the bottom of said accumulator, and in which said heatexchange coil is connected in said seventh tube in series with saidcapillary tubes.

4. A heat pump as claimed in claim 1 in which there is provided a heatexchange coil in the bottom of said accumulator, and in which said heatexchange coil is connected in said seventh tube in series with saidrestrictors.

5. A heat pump comprising a refrigerant compressor, reversal valve meansconnected to the discharge side of said compressor, an outdoor air coilconnected to said reversal means, an indoor air coil connected to saidreversal means, a suction line accumulator connected to said reversalmeans, a suction gas tube connecting said accumulator to the suctionside of said compressor, a second tube having a relatively smallresistance to refrigerant flow in heat exchange contact with saidsuction gas tube, means including a first fixed restrictor having arelatively large resistance to refrigerant fiow connected to saidoutdoor coil and to one end of said second tube, and means including asecond fixed restrictor having a relatively large resistance torefrigerant flow connected to said indoor coil and to the other end ofsaid second tube, said restrictors serving as two-way expansion means.

6. A heat pump as claimed in claim 5 in which said restrictors arecapillary tubes.

7. A heat pump as claimed in claim 6 in which there is provided a heatexchange coil in the bottom of said accumulator, and in which said heatexchange coil is connected in said second tube in series with saidcapillary tubes.

8. A heat pump as claimed in claim 5 in which there is provided a heatexchange coil in the bottom of said accumulator, and in which said heatexchange coil is connected in said second'tube in series with saidrestrictors.

References Cited by the Examiner UNITED STATES PATENTS 2,342,566 2/ 1944Wolfert 62-324 2,589,384 3/1952 Hopkins 62-160 3,110,164 11/1963 Smith62'324 3,128,607 4/1964 Kyle 62-324 3,153,913 10/1964 Brody 62324WILLIAM J. WYE, Primary Examiner.

1. A HEAT PUMP COMPRISING A REFRIGERANT COMPRESSOR, REVERSAL VALVEMEANS, A DISCHARGE GAS TUBE CONNECTING THE DISCHARGE SIDE OF SAIDCOMPRESSOR TO SAID VALVE MEANS, AN OUTDOOR AIR COIL, A SECOND TUBECONNECTING SAID VALVE MEANS TO SAID COIL, AN INDOOR AIR COIL, A THIRDTUBE CONNECTING SAID VALVE MEANS TO SAID INDOOR COIL, A SUCTION LINEACCUMULATOR, A FOURTH TUBE CONNECTING SAID VALVE MEANS TO SAIDACCUMULATOR, A FIRST FIXED RESTRICTOR HAVING A RELATIVELY LARGERESISTANCE TO REFRIGERANT FLOW, A FIFTH TUBE HAVING A RELATIVELY SMALLRESISTANCE TO REFRIGERANT FLOW CONNECTING SAID RESTRICTOR TO SAIDOUTDOOR COIL, A SECOND FIXED RESTRICTOR HAVING A RELATIVELY LARGERESISTANCE TO REFRIGERANT FLOW, A SIXTH TUBE HAVING A RELATIVELY SMALLRESISTANCE TO REFRIGERANT FLOW CONNECTING SAID SECOND RESTRICTOR TO SAIDINDOOR COIL, A SEVENTH TUBE HAVING A RELATIVELY SMALL RESISTANCE TOREFRIGERANT FLOW CONNECTING SAID RESTRICTORS, AND A SUCTION GAS TUBECONNECTING SAID ACCUMULATOR TO THE SUCTION SIDE OF SAID COMPRESSOR, SAIDSEVENTH TUBE BEING IN HEAT EXCHANGE CONTACT WITH SAID SUCTION GAS TUBE,SAID RESTRICTORS SERVING AS TWO-WAY EXPANSION MEANS.